code: def testIsExtension(self):
      self.assertTrue(
          unittest_pb2.optional_int32_extension.is_extension
      )
      self.assertTrue(unittest_pb2.TestRequired.single.is_extension)
  
      message_descriptor = unittest_pb2.TestRequired.DESCRIPTOR
      non_extension_descriptor = message_descriptor.fields_by_name["a"]
      self.assertTrue(not non_extension_descriptor.is_extension)
  
imports: import unittest
  from google.protobuf.internal import test_bad_identifiers_pb2
  from google.protobuf import unittest_custom_options_pb2
  from google.protobuf import unittest_import_pb2
  from google.protobuf import unittest_import_public_pb2
  from google.protobuf import unittest_mset_pb2
  from google.protobuf import unittest_pb2
  from google.protobuf import unittest_no_generic_services_pb2
  from google.protobuf import service
label_desc: Use image node_id 7 for calling the GeneratorTest obj's underlying member method code with example usage: obj.testIsExtension() without return types